The possibility to determine the position of a mobile terminal such as a user equipment (UE) has enabled application developers and wireless network operators to provide location based, and location aware, services. Examples of those are guiding systems, shopping assistance, friend finder, presence services, community and communication services and other information services giving the mobile user information about their surroundings.
In addition to the commercial services, the governments in several countries have put requirements on the network operators to be able to determine the position of an emergency caller. For instance, the governmental requirements in the USA (FCC E-911) mandates that it must be possible to determine the position of a certain percentage of all emergency calls, with high accuracy and within a pre-specified maximum time. Terrestrial positioning methods are necessary for use as a backup when celestial positioning methods (e.g., GPS, Galileo) are not available or the UE is not capable of celestial positioning methods.
As will be described in further detail below, use of split antennas can impair the terrestrial positioning methods such that the terrestrial positioning are not sufficiently accurate. This in turn can lead to disadvantages both commercially and in being able to meet government requirements for an operator.